CVE-2016-10186 in DWR-932B
Summary
by MITRE
An issue was discovered on the D-Link DWR-932B router. /var/miniupnpd.conf has no deny rules.
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Analysis
by VulDB Data Team • 05/16/2026
The vulnerability identified as CVE-2016-10186 affects the D-Link DWR-932B wireless router model and represents a significant network security flaw within the router's Universal Plug and Play UPnP service implementation. This issue stems from the absence of deny rules in the /var/miniupnpd.conf configuration file, which is a critical component of the miniupnpd daemon responsible for handling UPnP functionality on the device. The UPnP service allows devices on a local network to automatically configure port mappings and forward traffic to specific internal hosts, but when improperly configured without proper access controls, it creates an exploitable attack surface.
The technical flaw manifests in the router's default configuration where the miniupnpd service lacks proper access control lists or deny rules that would normally restrict external access to the UPnP functionality. This configuration allows unauthorized external entities to interact with the UPnP service and potentially manipulate port mappings, create unauthorized network access points, or redirect traffic to malicious endpoints. The absence of deny rules in the /var/miniupnpd.conf file essentially creates an open door for attackers to exploit the UPnP service without proper authentication or authorization mechanisms in place. This vulnerability falls under the CWE-284 access control weakness category, specifically addressing improper access control in network services.
The operational impact of this vulnerability extends beyond simple network configuration issues and presents a substantial risk to network security and privacy. Attackers can leverage this flaw to gain unauthorized access to internal network resources by manipulating the UPnP service to forward ports to internal hosts, potentially enabling them to bypass firewall rules and gain access to sensitive systems. The vulnerability also creates opportunities for man-in-the-middle attacks, port scanning, and network reconnaissance activities that could lead to more severe exploitation. According to ATT&CK framework, this represents a privilege escalation and persistence technique where attackers can establish unauthorized network access points and maintain long-term access to the network infrastructure. The vulnerability is particularly concerning because it affects a widely deployed consumer router model and operates at the network infrastructure level, potentially allowing attackers to compromise entire home or small office networks.
Mitigation strategies for this vulnerability require immediate configuration changes to establish proper access controls and network segmentation. Network administrators should implement deny rules in the /var/miniupnpd.conf file to restrict external access to the UPnP service and ensure that only authorized internal hosts can utilize the port mapping functionality. The recommended approach includes configuring the miniupnpd service to only accept connections from specific internal IP addresses or implementing a whitelist-based access control mechanism. Additionally, organizations should disable the UPnP service entirely if it is not required for network operations, as this eliminates the attack surface entirely. Security best practices dictate that routers should be configured with default-deny policies, where all access is denied unless explicitly permitted, and regular security audits should verify that network services are properly configured with appropriate access controls. This vulnerability demonstrates the critical importance of secure configuration management and proper network segmentation in preventing unauthorized access to core network infrastructure components.